This present invention relates to networks having standby agents. More specifically, it relates to third generation networks and standby home agents.
Various types of telecommunication networks have evolved over the past few years. For example, third generation networks have evolved that seek to integrate wireless networks to other networks, such as the Internet. Such integration allows users of wireless networks to access Internet services.
In one example of a third generation network, a mobile node (such as a cellular phone) communicates via an air interface to a radio access network (RAN). The RAN is coupled to an IP network via an interface. The RAN comprises base stations, switches, and control entities, which allow a mobile device to communicate with fixed, landline devices. The IP network can be coupled to various servers that provide access to other networks, such as the Internet.
The IP network includes, for example, switches and network management entities, which route IP packets through the IP network. The management entities include managers and agents. A manager may be an entity that can query agents, receive responses from the agents, and send instructions to these agents. An agent responds to the requests and performs management functions on various resources in the network. The agent interprets information contained in a management information base (MIB). The MIB contains information that relates to the managed resource.
The mobile node can move from a xe2x80x9chomexe2x80x9d network to xe2x80x9cforeignxe2x80x9d networks. The home network may need to forward packets of information to the mobile node in a foreign network. If information is to be forwarded to the mobile node, then the network needs to know the location of the mobile node.
The mobile node has a static address, called a home address, which is used to identify the mobile node so that packets of information can be routed to and from the mobile node. The home address makes it appear that the mobile node is able to receive data on the home network. A home agent exists on the home network, which helps to manage the activities of the mobile node and other mobile nodes having a home address on the home network. As the mobile node moves to foreign networks, the home agent forwards received packets destined for the mobile node and arranges to deliver these packets to the mobile node at its location in the foreign network.
Whenever the mobile node moves to a foreign network, it registers its new foreign agent address with its home agent. To transmit a packet from the home network to the new foreign agent address requires that the packet be modified. This reconstruction, or tunneling, bypasses the usual effects of IP routing.
Foreign agents help maintain communications over links utilizing a point-to-point protocol (PPP). In order to establish communications over a point-to-point link, each end of the link must first send packets that help configure the link. After the link has been established, the link can be authenticated before the transmission of packets. The point-to-point protocol provides a standard method of encapsulating Network Layer protocol information over point-to-point links. The point-to-point protocol encapsulates data over data link connections; establishes, configures, and tests the data link connection; and establishes and configures different network-layer protocols.
Home agents may utilize various databases in their operations. Home and foreign networks may also have collection of databases, which store various types of information. Managing dispersed serial line and modem pools for large numbers of users can create the need for significant administrative support. Since modem pools link a user to other users, authorization, security, and accounting functions are required. This can be accomplished by managing a single database of users rather than multiple databases. A single database allows for authentication as well as configuration functions detailing the type of service, for example, PPP service, provided to a user.
Home agents and foreign agents may advertise their availability to mobile nodes on each communication link for which they provide service. A mobile node can send an inquiry on the link to learn if any prospective agents are present. When the mobile node is away from its home network, it registers its xe2x80x9ccare-of addressxe2x80x9d with its home agent. Depending on its method of attachment, the mobile node will register either directly with its home agent, or through a foreign agent, which forwards the registration to the home agent.
Foreign agents and home agents advertise their presence to mobile nodes via agent advertisement messages. A mobile node may solicit an agent advertisement message from any foreign or home agent through an agent solicitation message. A mobile node receives these agent advertisements from the foreign or home agent and determines whether it is on its home network or a foreign network. When the mobile node detects that it is located on its home network, it operates without mobility services. If returning to its home network from being registered elsewhere, the mobile node de-registers with its home agent, through exchange of a registration request and registration reply message with it. When a mobile node detects that it has moved to a foreign network, it obtains a care-of address on the foreign network. The mobile node operating away from home then registers its new care-of address with its home agent through exchange of a registration request and registration reply message with it, possibly via a foreign agent. Information sent to the mobile node""s home address are intercepted by its home agent, tunneled by the home agent to the mobile node""s care-of address, received at the tunnel endpoint (either at a foreign agent or at the mobile node itself), and finally delivered to the mobile node.
In the reverse direction, information sent by the mobile node is generally delivered to its destination using standard IP routing mechanisms, not necessarily passing through the home agent. When away from home, tunneling is used to hide a mobile node""s home address from intervening routers between its home network and its current location. The tunnel terminates at the mobile node""s care-of address. The care-of address must be an address to which information can be delivered via conventional IP routing. At the care-of address, the original information is removed from the tunnel and delivered to the mobile node.
The Remote Authentication Dial In User Service (RADIUS) protocol for the Internet carries authentication, authorization, and configuration information between a Network Access Server, which desires to authenticate its links, and a Shared Authentication Server.
A network access server operates as a client of RADIUS. The client is responsible for passing user information to designated RADIUS servers, and then acting upon the request that is returned. RADIUS servers are responsible for receiving user connection requests, authenticating the user, and returning all configuration information necessary for the client to deliver to the user. A RADIUS server can act as a proxy client to other radius servers or other kinds of authentication servers.
Home agents can be dropped for a number of reasons. For example, hardware or software failure may result in the home agent malfunctioning and being dropped by the network. If a home agent fails, calls can be dropped. What is needed is a system and method whereby the failure of a home agent does not result in dropped calls. What is also needed is a system and method whereby the transfer from the failed home agent to the new home agent is transparent to the user. That is, the call flow should not be interrupted by the transfer.
The invention relates to a hot standby feature in a telecommunication network that does not impact a mobile node session.
In one embodiment of the present invention, a mobile node is coupled via an IP network having a home agent to various entities. These entities may include PDSNs, servers, and AAA nodes. Other examples of entities are possible. A home agent control node (HACN) and redundant home agents are also coupled to the IP network.
The mobile node registers its identity through the HACN. For example, each mobile node may have a registration mobility binding record (MBR) snapshot. The MBR snapshot for each mobile is recorded in a HACN, a standby for the HACN, and a home agent.
Periodically, the HACN polls its home agents to determine whether a particular home agent has failed. For example, the home agent may broadcast a heartbeat signal, which indicates that the home agent is functioning properly. The absence of a heartbeat signal indicates that the home agent has failed.
In the case of a home agent failure, the MBR snapshots associated with the failed home agent are transmitted from the HACN to a redundant home agent. The redundant home agent waits until all the proper MBR snapshots are downloaded from the HACN. When downloading is complete, the redundant home agent is activated and begins to broadcast the heartbeat signal.
In another aspect of the present invention, the HACN also has an associated HACN standby. Each registration is distributed over all HACNs. In case of the failure of one HACN, the standby HACN will replace the failed HACN.
The foregoing and other features and advantages of an illustrative embodiment of the present invention will be more readily apparent from the following detailed description, which proceeds with references to the accompanying drawings.